This invention relates to a surgical drainage system and more particularly, to an apparatus designed to drain fluids from a body cavity.
It is essential for normal breathing that the space within the pleural cavity surrounding the lungs be free of liquid and be subject to a negative pressure so as to draw the lungs outwardly to fill the pleural cavity. Any invasion of the pleural cavity such as lung surgery, foreign objects piercing the ribcage or pleurisy, generate fluids in the pleural cavity which obstruct normal breathing and it is necessary to provide means for removing these fluids and at the same time to maintain the desired degree of negative pressure within the pleural cavity.
The basic apparatus which has been used for this purpose is an apparatus such as shown in U.S. Pat. Nos. 3,363,626 and 3,363,627. This apparatus is known as an underwater drainage apparatus and provides basically three chambers, one chamber comprising a collection chamber for collecting the fluids drained from the pleural cavity, a second chamber known as an underwater seal chamber which protects the pleural cavity from being subject to atmospheric pressure, and a third chamber known as a pressure manometer chamber which regulates the degree of negative pressure within the pleural cavity. This type of apparatus has been highly successful in both removing fluids from the pleural cavity and in maintaining the desired degree of negativity within the pleural cavity. However, the attachment of an underwater drainage apparatus to a patient's pleural cavity in effect enlarged the pleural cavity to the extent of the size of the collection chamber. This so called "dead air space" within the collection chamber caused the patient additional effort in breathing. While under ordinary circumstances this additonal effort would not be a problem but, in the case of a patient in a weakened condition or a child, the additional air space imposed by the collection chamber may cause severe difficulties in breathing.
The drainage system disclosed in U.S. Pat. No. 4,015,603 was developed to provide a solution to the problems outlined above. Specifically, the underwater drainage apparatus disclosed in Patent No. 4,015,603 limits the dead air space created by attachment of a drainage apparatus by locating the underwater seal directly at the end of the thoracotomy tube. Thus, the volume of the collection chamber itself did not constitute an additional volume in the pleural cavity. This device has proven highly successful but, the location of the underwater seal chamber at the lower end of the thoracotomy tube created a further problem in certain unusual circumstances. In the case of a patient having a blockage in the bronchial tubes, such that the patient was having severe problems in getting air into the lungs, exceedingly high negativity was being created in the pleural cavity. Such high negativity caused the fluid in the underwater seal to be drawn upwardly through the thoracotomy tube and, if the degree of negativity was sufficiently high, it was possible for fluid to reenter the pleural cavity. This condition of fluid from the underwater seal chamber reentering the pleural cavity could cause infection or otherwise create problems for the patient. In addition, it was possible to entirely lose the seal provided by the underwater seal chamber during periods of high negativity in the pleural cavity. The loss of the water seal has the potential for serious damage in the event the suction becomes disconnected or the device is used as a two bottle system with the collection chamber open to atmosphere.